Studies on tissue-speciflc pathogenicity of picoronaviruses

伪狂犬病病毒科是一个正链RNA病毒大家族。这个家族中的每种病毒的致病性都有很大的不同。例如，脊髓灰质炎病毒、柯萨奇病毒、甲型肝炎病毒、鼻病毒分别引起急性脑炎、心肌炎、肝炎和普通感冒。本研究旨在阐明脊髓灰质炎病毒组织特异性致病性的分子机制。1.获得表达人脊髓灰质炎病毒受体(PVR)基因的转基因小鼠。PVR被认为是限制寄主范围和组织嗜性的主要决定因素。为了确定PVR表达对组织趋向性的影响，我们培育了两只表达PVR的转基因小鼠，它们具有不同的分布模式。在HG-PVR小鼠模型中，PVR基因的表达有其自身的启动子，而PVRIS只分布在神经元中，而不分布在胶质细胞中。在CAG-PVR小鼠中，PVRIS表达广泛。在脑内接种脊髓灰质炎病毒后，前者出现类似人类脊髓灰质炎的瘫痪疾病并死亡，而后者在没有瘫痪的情况下存活下来。这些结果提示PVR的表达模式在脊髓灰质炎病毒的神经发病机制中具有重要意义。2.中国脊灰病毒的致病性。我们生产了脊髓灰质炎病毒和CVB3病毒之间的嵌合病毒。具有CVB3 5‘非编码区的脊髓灰质炎病毒嵌合体具有与脊髓灰质炎病毒相似的神经致病特性。具有脊髓灰质炎病毒5‘非编码区的CVB3嵌合体不具有神经致病性。这些结果提示了各病毒编码区对于组织特异性感染的重要性。3.肠道病毒(EV)71株感染性基因的构建。EV71也是一种嗜神经性病毒，没有得到广泛的分析。我们从一例致死性脑炎死亡患者的直肠拭子中分离到一株EV71毒株SK006/Malaysia，我们构建了该毒株的感染性cDNA克隆。该cDNA克隆将成为研究EV71嗜神经性的有力工具。

Piconraviridae is a large family of positive-stranded RNA viruses. The pathogeniciy of each virus in this family is quite different. For example, poliovirus, coxsakievirus, hapatitis A virus, rhinovirus cause acute encephalitis, myocarditis, hepatitis and common cold, respectvely. Aim of our research is to elucidate molecular mechanism to determine tissue-specific pathogenicity of pjcoraaviruses.1.Production of transgenic mice expressing human poliovirus receptor (PVR) gene. PVR has been considered as a major determinant of host range restriction and tissue tropism. To determine the influence of PVR expression on the tissue tropism, we have produced two transgenic mice in which PVR is expressed with a different distribution pattern. In one model, hg-PVR mouse, PVR gene is expressed with its own promoter and PVRis distributed only in neurons but not glial cells. In the other, CAG-PVR mouse, PVRis expressed ubiquitously. After intracerebral inoculation of poliovirus, the former showed a paralytic disease that resembles human poliomyelitis and died, while the latter survived without paralysis. The results suggested importance of PVR expression patterns on neuropathogenesis of poliovirus.2.Pathogenicity of chmeric viruses. We produced chimeric viruses between poliovirus and CVB3 virus. A poliovirus chimera having 5'-noncoding region of CVB3 showed neuropathogenic property similar to poliovirus. A CVB3 chimera having 5'-noncoding region of poliovirus did not show neuropathogenic property. The results suggested the importance of coding region of each virus for the tissue-specific infection.3.Construction of Infectious cDNA for enteorhlrus (EV)71. EV71 is also a neurotropic virus, which is not analysed extensively. We have constructed an infectious cDNA clone for an EV71 strain, SK006/Malaysia, which was isolated from a rectal swab of a patient died of fatal encephalitis. This cDNAclone will be a powerful tool to investigate neurotropism of EV71.